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Exam 1 Practice Problems

Exam 1 Practice Problems. SOLUTIONS. 1. Show Output. for i in range(5): print( i * i ) 0 1 4 9 16 for d in [3,1,4,1,5]: print( d,end =' ') 3 1 4 1 5 (c) for i in range(4): print("Hello") Hello Hello Hello Hello. 1. Show Output.

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Exam 1 Practice Problems

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  1. Exam 1 Practice Problems SOLUTIONS

  2. 1. Show Output • for i in range(5): print(i*i) 0 1 4 9 16 • for d in [3,1,4,1,5]: print(d,end=' ') 3 1 4 1 5 (c) for i in range(4): print("Hello") Hello Hello Hello Hello

  3. 1. Show Output • for i in range(5): print(i,2**i) 0 1 1 2 2 4 3 8 4 16 • for c in ['g','o','o','d','b','y','e']: print(c,sep='',end='') goodbye (f) D = {'Prof':'Tindell','Dept':'CSE','School':'USF','City':'Tampa'} for k in D.keys(): print(k,'is',D[k]) Prof is TindellDept is CSE School is USF City is Tampa

  4. 1. Show Output (g) L = ['To','be','or','not','to','be'] print(' '.join(L)) To be or not to be (h) L = ['6','12','2012'] print('/'.join(L)) K = L[-1:]+L[:2] print('-'.join(K)) 6/12/20122012-6-12 (i) S = "Elementary my dear Watson" print(S.split()) ['Elementary','my','dear','Watson'] L[-1:] = ['2012']L[:2] = ['6','12'] L[-1:]+ L[:2] = ['2012','6','12']

  5. 1. Show Output ((j) S = """Well, Stanley, isn't this a fine kettle of fish you've gotten me into""" print(S.splitlines()) ["Well, Stanley,","isn'tthis","a fine", "kettle of fish","you've gotten me into"]

  6. 1. Show Output (k) i = input("Enter an integer: ") j = input("Enter another integer: ") print("Adding them together we get",i+j) Suppose the user enters 25 at the first prompt and 10 at the second prompt. Show the output. Adding them together we get 2510 • L = ['to','be','or','not','to','be'] for k in sorted(L):print(k) bebe not or to to

  7. 1. Show Output • print(11/4,11//4,11%4) 2.75 2 3 (n) S = 'To be or not to be'S.replace('be','have been') print(S) To be or not to be (o) names1 = ['Amir','Barry','Charles','Dao'] print(names1[-1][-1]) o (p) names1 = ['Amir','Barry','Charles','Dao'] loc = names1.find("Edward") print(loc) -1 names[-1] = 'Dao''Dao'[-1] = 'o'

  8. 1. Show Output • names1 = ['Amir','Barry','Charles','Dao']names2 = [x.lower() for xin names1] names2 = ['amir','barry','charles','dao'] print(names2[2][0]) c (r) confusion = {} confusion[1] = 1 confusion['1'] = 2 confusion[1] += 1 sum = 0 for k in confusion: sum += confusion[k] print(sum) 4 names2[2]

  9. 1. Show Output (s) name = "snow storm" print(name[6:8]) to (t) name = "snowstorm" name[5] = 'X' print(name) ERROR – OBJECTS OF TYPE str ARE IMMUTABLE (u) for i in range(2): print(i,end=' ') for i in range(4,6): print(i,end=' ') 0 1 4 5

  10. 1. Show Output (v) x = True y = False z = False if x or y and z: print('Yes') else: print('No') ) Yes True or (False and False) = True or False = True

  11. 1. Show Output (w) x = True y = False z = False if not x or y: print(1)elif not x or not y and z: print(2)elif not x or not y or not y and x: print(3) else: print(4) 3 (not True) or False = False or False = False (not True) or ((not False) and False) = False or (True and False) = False or False = False (not True) or (not False) or ((not False) and True) = False or True or (True and True) = True

  12. 1. Show Output (x) L = [3,1,1,5,3,2,2,4] S = set(L) print(len(S)) 5

  13. 2. Suppose we execute the following statemenst D = { } S = 'one' L = ['one','two'] T = ('one','two') For each of the following, indicate whether it is a valid Python statement; if it is not valid, explain why. D[S] = 'bacon' valid D[T] = 'bacon'valid D[L] = 'bacon' invalid – dictionary keys must immutable, lists are mutable D[5] = 'bacon' valid

  14. 3. Write a python code segment that prompts for and inputs positive integers where the user indicates the end of input by entering the value 0; prints out the number of positive integers that were entered, their sum and their average value. number_of_entries= 0 sum = 0 print("Enter a sequence of positive integers, 0 to quit") n = int(input("Enter a postive integer, or 0 to stop: ")) while n != 0: number_of_entries+= 1 sum += n n = int(input("Enter a postive integer, or 0 to stop: ")) average = sum/ number_of_entries print("You entered", number_of_entries,"values") print("Their sum is",sum) print("and their average value is",average)

  15. 4. Write a complete Python program that CHALLENGING • Prompts for and inputs a string named S • prints the total number of alphabetic characters in S • for each alphabetic character that appears in S, prints the character, the number of times that character appears in S and its relative frequence (fraction of the total) Note: upper and lower case versions of a letter are to be considered the same S = input("Enter a string: ") S = S.lower() X = {c for c in set(S) if c.isalpha()} D = {} total = 0 for c in X: D[c] = S.count(c) total += D[c] print("Total number of alphabetic characters: ",total) for c in sorted(D.keys()): print(c,D[c],D[c]/total,sep='\t')

  16. Alternate solution to problem 4 S = input("Enter a string: ") S = S.lower() # X = {c for c in set(S) if c.isalpha()} L = [] for c in S: if c.isalpha() and c not in L:L.append(c) D = {} total = 0 #for c in X: for c in L: D[c] = S.count(c) total += D[c] print("Total number of alphabetic characters: ",total) for c in sorted(D.keys()): print(c,D[c],D[c]/total,sep='\t')

  17. 5. Consider the following function with two parameters, both strings: def mystery(s,p):i = s.find(p) if i == -1: return False while True:old_i = ii = s.find(p,old_i+1) if i == -1: return Falseelifi < old_i+len(p): return True Describe in words what this function does. That is, complete the following sentence: mystery(s,p) returns True if and only if s contains two overlapping substrings equal to p # no substring equal to p # remember previous index # no more substrings equal to p # found overlapping strings

  18. Write a complete Python program that prompts for and inputs a time in 12-hour format, then prints the same time in 24-hour format S = input("Enter a time in twelve-hour format: ") comps = S.split() hourstr, minutestr = comps[0].split(':') hour,minute = int(hourstr),int(minutestr) if comps[1] == 'pm': hour += 12 elif hour == 12: hour = 0 print('Time in 24-hour format: ',hour,':',minute,sep='') hour,minute= [int(k) for k in comps[0].split()] '4:25 pm' comps = ['4:25','pm'] comps[0] = ['4:25'] comps[1] = ['pm'] hourstr = '4' minutestr = '25' hour = 4 minute = 25 hour = 16 Time in 24-hour format: 16:25

  19. 7. Write a complete Python program that prompts for and inputs a time in 24-hour format and prints the same time in 12hour format S = input("Enter a time in twenty-four hour format: ") hourstr, minutestr = S.split(':') hour,minute = int(hourstr),int(minutestr) ampm = "am" if hour < 12 else "pm" if hour > 12: hour -= 12 elif hour == 0: hour = 12 print("Time in 12-hour format: ",hour,':',minute,' ',ampm,sep='')

  20. Write a Python program that inputs a string containing only lower-case letters and spaces, then constructs a dictionary whose keys are the distinct words in the string and whose value for a word is the number of times the word appears in the string. After that, it prints the contents of the dictionary by printing for each word in the string a line containing the word, a tab and the number of times the word appears in the string. You must print the lines in ascending alphabetic order of the words. S = input("Enter a string: ") D = {} L = S.split() for w in L: if w in D: D[w] += 1 else: D[w] = 1 for c in sorted(D.keys()): print(c,D[c],sep='\t') D[w] = L.count(w)

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